Earth working implement and power lift mechanism therefor



Dec. 13, 1960 w. J. MELDAHL EARTH WORKING IMPLEMENT AND POWER LIFTMECHANISM THEREFOR 4 Sheets-Sheet 1 Filed March 19, 1956 nvenfoz WALDEMAR J: MELDAHL Dec. 13, 1960 MELDAHL 2,964,114

EARTH WOR IN LEMENT AND POWER LIFT MECH SM THEREFOR Filed March 19, 19564 Sheets-Sheet 2 f7nuento1 WA LDEM 4 R J ME LDA HL Q'f-tat 115 Dec. 13,1960 w. J. MELDAHL 2,964,114

EARTH WORKING IMPLEMENT AND POWER LIFT MECHANISM THEREFOR 4 Sheets-Sheet3 Filed March 19, 1956 f7nuen ALDEMAR J. MEZDAHL Dec. 13, 1960 w. J.MELDAH 2,964,114

EARTH WORKING IMPLEMENT POWER LIFT MECHANISM THEREFOR Filed March 19,1956 4 Sheets-Sheet 4 WA E DIgMAR i'h'ifibA HL awimfiamba CbHazn egilnited States Patent EARTH WDRKING IMPLEMENT ANDPOWER LIFTMECHANISMTHEREFOR Waldemar J. Meldahl, Green Bay, Wis., assignor to J. I.

Case Company, Racine, Wis., a corporation of Wisconsin Filed Mar. 19,195$,Ser. N... 572,541,

4 Claims. or. 172-487) in the direction of lighter weight, greaterstrength and rigidity, together with ease and economy of fabrication.Another object is to provide an advantageous arrangement of independentground Working rigs carried by and propelled from the frame arrangement.

Another object is to provide an arrangementjof linkage for convenientlyraising such rigs and adjusting the working depth thereof. V

Another object is to provide improvements in said mechanism whichprovide for advantageous operation of the usual self-interrupting powerlift clutch. Another object is to provide improvements'in such aself-interrupting clutch to more properly adapt it to the specialconditions commonly encountered when used with an implement of thistype.

Other objects and advantages will appear from the following descriptionin which like reference characters refer to the same partsthroughoutvthe description and accompanying drawings in which:

Figure 1 is a perspective view of an implement embodying the inventiontaken from the rear and somewhat to the left.

Fig. 2 is a perspective view'on a largerscale, taken fromthe right sidelooking slightly tothe rear with parts removed and others broken away toshow what lies v beneath. I

Fig. 3 is a right side elevation of a clutch indicated in Fig. 2 onalargerscale with parts removed. and others broken away. V Fig. 4 is asimilar view but with other parts removed and certain underlyingparts'sh-own in brokenlines.

Fig. 5 is a left side elevation of a portion of Fig. .4. Fig. 6is anelevation of the mechanism shown in Fig. 5 as seen from the left of Fig.5.

Fig. 7 is an elevation of the mechanism shown in Fig. 5 as seen from theright of Fig. 5.

Fig. 8 is a view similar to Fig. 4 diagrammatic in I character andshowing a modified form of the construction.

Fig. 9 is a similar view position.

Turning to Fig. 1, the machine comprises a frame, generally designatedas F, carried by ground engaging wheels W1 and W2 and propelled by adrawbar D, frame F carrying a plurality of soil working rigs as Rconnected thereto by linkage systems L and raised and lowered by a powerlift mechanism generally designated as P, frame showing the partsin'another F being attached to a tractor, not shown, through drawbar D,thereby propelling rigs R which are dropped into engagement with soil'or lifted out of contact therewith 7 by mechanism Pas desired or ascircumstances require.

Frame F comprises, in the present instance, a relatively large pipe ortube 10 having welded or otherwise fixed therewith a pair of supportingbrackets 12 and 14 on which are journaled above-mentioned wheels W1 andW2, drawbar D being composed of suitable longitudinal members 16 fixedin a suitable manner to plates 18 and 20 also permanently united withtube 10. Drawbar D also has hitch plates 22 adjustably carrying a hitchpin assembly 24 which is of well-known type not necessary to furtherdescribe. With hitch assembly 24 connected to a tractor, the structureso far described will be stable and will travel along the ground behindthe tractor.

Frame F carries, in the illustrative embodiment, three rigs R, which areessentially alike. Referring to the left hand rig as shown in Fig. 1,tube 10 has a substantially vertical member, in the present instanceanoutwardly open channel 26, permanently united therewith and'havingpivoted thereto at 28 and 30 respectively upper and lower parallel links32 and 34. joined at their rearward extremities by a strut '36 formingpart of a yoke-like member generally designated as 38. Yoke 38 has astrut portion 40'permanently united'to atool bar p'ortion 42 to. whichabove-mentioned strut portion 36 is" also connected in the neighborhoodof apivotal connection 44 between above-mentioned link 34 and, strut 36.Link 32 is also connected to strut 36 at apivotal'connection 46. As willbe apparent, since plate 26'and strut 36 are of substantially the samelength, while, links 32 and 34 are also of substantially the samelength, .these parts define a parallelogram-type of linkage wherein toolbar portion 42 may be raised and lowered relative to frame F withswinging of links 32 and 34 but substantially Without change in itsangular relation to the ground. I

A companion link 48 to link 34 is pivoted to a bracket 50 and acompanion link 52 to link 32 is pivoted to a bracket 54 permanentlyunited to tube 10, links 48 and 52 being pivoted at their rearward endsto yoke 38 as in the case of links 32 and 34. In this way a stablearrange.- rnent'is provided supporting tool bar.42 for free up-anddownfloating movement butmaintaining it at all times 'in a positionsubstantially parallel to tube 10.

along with tool bar 42 arid [rig frame 56 as willbe apparent. It willalso be apparent that, because of the parallel motion or fixed angularrelation of toolbar 42 to the ground, the working angle of tools 66 willnot be disturbed by any adjustments in the depth of working.Furthermore, since tools may be disposed at various points ahead of andbehind each other, tools nearer and further from pivots'46 and 44 willnevertheless be raised and lowered substantially identical amounts whenyoke 38 and toolbar 42 are adjusted up and down.

A rig frame generally designated as 68 defines a second or right-handrig' located generally at the opposite end of tube 10 from rig frame 56,this right-hand rig being substantially identical with the left-hand rigjust described so that further description of it is unnecessary. A'third rig' frame 70, however, is located between those justdescribed'and is fixed to a tool bar 72 which is carried on upper andlower parallel links 74 and 76 respectively on the left side and 78 and80 on the right. Links 74 and .78 are pivotally connected to a yokeSZhaving upwardly directed struts $4 and 86 extending '3 downwardly toandpermanently united with tool bar 72. As will be apparent, yoke 82 andthe several links form the elements of a parallelogram linkage, as inthe case of yoke 38, so that gang frame 70 is free to move up and downwhile at the same time being caused to maintain a predetermined angularrelation to the ground. The several rig frames, '68, and 70 are thusfree to rise and fall or float and they are also [readily raised out ofworking position by suitable mechanism as follows.

A generally upwardly extending lever 88 is pivoted on a pin 90 engagedwith above-mentioned plates 18 and 20 and may be rocked forward and backwith substantial force by a mechanism to be described. Lever 88 ispreferably fabricated of suitable structural elements and includes apivot pin 92 to which are pivoted a plurality of extensible strutsgenerally designated as 94, 96, and 98, one for each of rig frames 56,68, and 70, strut 94 forming or being fixed with pivot 46, strut 96being connected with theequivalent pivotal connection for the right-handrig while strut 98 is anchored to a yoke 100 which connects with apivotal connection .102 between yoke 82 and links 74 and 78. As will nowbe apparent, forward rocking of lever 88 will pull on struts 94, 96, and98 and cause upward swinging of the three rig frames along with theirrespective parallel linkage sets.

Turning to Fig. ,2, struts 94, 96, and 98 are essentially similar andthe description of one should sufiice for all. Strut 96 comprises anouter tubular section 104 having an eye or pivot bearing portion 106journaledon abovementioned pivot 92. A rod portion 108-is slidablewithin tubularportion 104,- extending outwardly axially thereof andforming or in connection with a pivot 110, Fig. 1, corresponding toabove-mentioned pivot 46. Tubular portion 104 provides a slot 112, Fig.2, in which is slidable a cap screw or the like forming a motionlimiting stop 114 engaged in rod 108. In this manner rod 108 isprevented from sliding entirely out of tubular portion 104, while therod may slide further into tube 104 to the extent of the length of slot112. Thus it is possible for a pull to be exerted through strut 96,whereas if a thrust develops in the strut, it may collapse or. telescopea limited amount to relieve the compression. A spring 116 is compressedbetween a collar-118 fixed on rod 108 and the end of tube 104, a washer120 preferably being interposed as shown. In this way strut 96 isextended to its greatest possible length. I

Normally the weight of each rig and its linkage set will be imposed onits respective extensible strut and will put the strut in tension sothat stop 114 willrest in the outer extremity of slot 112. Occasionally;however, the reaction of the ground, depending upon the type'and numberof implements 66, will cause an upward tendency in the rig frame whichwill not only relieve the strut of any weight but may actually tend tocompress the strut. Such force is yieldingly resisted by spring 116butif the force is sufficient the rig may rise with a compressing movementof spring 116 and with movement of stop 114 in slot 112 toward the rightas seen in Fig. 2. There is thus, under these conditions, downwardpressure on the implement tending to yieldingly hold it in the ground.

If the implement strikes a rock or other obstruction,

the rig is free to rise independently of the other rigs, withtelescoping movement of the associated strut and without developing anydestructive forces in the parts. We thus have a linkage which, byrocking movement in lever 88, will lift all three rigs simultaneously,whereas on the other hand the rigs are independent as far as floatingmovement is concerned and may rise to clear obstructions without anyinterference with each other. Furthermore, downwardpressure can beexerted on the rigs; as necessary without sacrificing this advantage.

A counterbalancing spring "122 is connected to a stud 124, Fig. 2, whichis anchored and adjustable 'by means of a nut 126 engaging a portion oflever 88, the other end of spring 122 being anchored in any suitablemanner I 4 to a bracket assembly 128 (Fig. l) fixed on drawbar D. Stud124 may be adjusted to cause spring 122 to exert a continuoussubstantial pull on lever 88 so as to continuously tend to lift rigs Rthrough struts 94, 96, and 98 and this pull may be adjusted from time totime by means of nut 126 as required by varying conditions.

Lever 88 may be rocked as necessary through a pitman link generallydesignated as 130 actuated by a crank 132 fixed on a shaft 134 carriedin bearing brackets 136 and 138, shaft 134 being caused to rotatesubstantially one-half turn from time to time by a self-interruptingclutch generally designated as 140. Clutch 140 receives motion fromground wheel W2 through a sprocket 142 driving a chain 144 which alsoengages and drives a sprocket 146 constituting part of clutch 140.

Returning to a description of pitman link 130 and its connections, thelink is bifurcated in character, and is provided with a slot 148 inwhich is slidable a trunnion pin 150 adjustable up and down in slot 148by means of a screw 152. At its upper end link 130 is guided in anarcuate path about abovementioned pin 90 by means of swingable links 154while other links 156, pivoted upon a pin 158 at theupper extremity oflever 88, connect with pin 150. At its lower end link 130 is journaledon a crankpin 160 (Fig. 1) on above-mentioned crank 132. With crank 132in the position shown in Fig. 2,.for example, adjustment of screw 152will cause movement of pm 150 with a maximum of swinging of links 156and a minimum lengthwise component of movement, while with crank 132 inits lowered position, indicated in, dotted lines, links 156 willapproach a position more nearly in line with link 130= so thatadjustment of screw 152 will cause a reduced amount of swinging with anincreased amount of lengthwise movement, thus providing an effectiveadjustment of working depth but resulting in a minimum amount of changein the raised position of the rigs. It will be apparent that lever 88and links 154 and 156 approximate the action of a bell crank as relatedto pitman link 130 so that half turns of crank 132 will cause swingingof lever 88 to a forward position corresponding toa raised position ofthe rigs and to a rearward position corresponding to a lowered positionof the rigs. Such movements are under the control of clutch 148.

Clutch 140, as best seen in Figs. 3 and 4, isof the type including acontinuously rotating part driven by abovementioned sprocket 146, inthepresent instance comprising a shell or cup member.16'2 providing aplurality of latch receiving recesses 164 continuously rotating byreason of the action of chain 144 and sprocket 146. A normallystationary part or latch plate 166 is fixed on shaft 134, on whichportion 162, is journaled, and has'an outer peripheral cam track orsurface 168 providing substantially diametrically'opposed detent notches170' and 172,

a trip member or follower portion 174 being engaged in notch 172 as seenin Fig. 3. A latch actuatinggbar 176 is rockably mounted about shaft 134and has a follower engaging surface 178 engaged with follower 174 and asimilar surface 180 flush with the surface of notch 170 in the positionof the parts shown in Fig. '3. Bar 176 is urged in a directiontoencroach upon notches 170 and 172 by means of a spring 182 anchored ona pin 184 and engagedfwith a hook element 186 offset from shaft 134 soas to impose a turning effort on bar 176. Bar 176 is connected through apivot 188, a link 190, and a pivot 192 with a latch lever 194 having alatchin'gportion 196 adapted to engage latch receiving recesses 164. Itwill be apparent that clockwise rocking of bar 176 will cause upwardswinging of latch 194 and engagement of portion 196 with the nearestrecess. Conversely, counterclockwise swinging of bar 176 will pullmember 196 out of its recess for a declutched condition of normallystationaryplate 166.

Latch lever .194 is pivoted on a fulcrum or pin 198* fixed on plate 166so that, when'latch'p'ortion 196 is engaged with any one of recesses164, plate 166 will be caused to rotate synchronously with member 162,but when bar 176 is forced by follower 174 away from the margins ofnotches 170 and 172, vas seen in Fig. 3, latch portion 196 is pulled'outof recesses .164 so that portion 162 is free to rotate while plate 166is locked by reason of engagement of follower 174 in .notch 172. It willbe noted that the distance from pivot 198 to pivot 192 is substantiallysmaller than that from shaft 134 to pivot 188. As a result, a slightangular movement of bar 176 will cause a relatively great angularmovement of latch lever 194. As well understood in the operation of thistype of device, follower 174 is momentarily withdrawn from notch 172,whereupon spring 182 causes rocking of bar 176 and engagement of portion196 as aforesaid to cause rotation of plate 166, clockwise in theembodiment disclosed. Follower 174 being immediately released, rideson'cam surface 168 until notch 17%) comes nearly into the position shownfor notch 172 whereupon surface 180 of bar 176 (which now encroachesupon notch 170) encounters follower 174 and no longer rotates with plate166, being prevented by contact with follower 174. A very few degrees ofrelative movement betweenbar 1-76 and plate 166 will cause multipliedmovement of latch lever 194 and disengagement thereof from any recess164 with which it happens to be engaged. Follower 174 is forcibly urgedinto the approaching notch as will be described and plate 166, now beingfree from'rotating element 162 is preferably forced by follower 174 aslight further amount until follower 174 seats in the approaching notch,thus locking plate 166 in the new position. The equivalent action, ofcourse, occurs when follower 174 is momentarily moved out of notch 170.Plate 166- is therefore promptly freed from rotating member 162 so thatfollower 174 may cause the necessary slight additional rotation. In thepast, certain difficulties have been encountered in this type of action.

Shaft 134, as heretofore described, is driven by plate 166 and actuatesabove mentioned link 136 through crank 132, and, as will be apparent,the downward thrust of link 130 upon crank 132 will cause a torque ortendency to rotate counterclockwise during the part of the rotationwhile link 130 is being raised and, if latch portion 196 is withdrawnfrom any detent recess 164 while crank 132 is in the act of raising link130, crank 132 and consequently plate 166 is freed for rotating. Plate166 will then tend to reverse unless forcibly held by follower 174. Ifthis happens, a few degrees of reverse rotation will .cause reengagementof portion 196. with another recess 164, whereupon plate 166 will againbe rotated in a clockwise direction until again released by the actionof bar'176 contacting follower 174. Plate 166 will then again reverseand the action will continue with annoying clicking and substantialunnecessary wear and consumption of power. To avoid this, applicant hasdevised an arrangement whereby crank 132 may be adjusted so that it willcause maximum raising of link 130 or go over center at any desired pointrelatively to the point of engagement of follower 174, and in practiceit isso adjusted as to reach the point where link 130 has just reachedor gone'slightly beyond its point of maximum lifting efiort on rigs R atthe time follower 174 engages notch-172. Thus, when latch portion 196 isdisengaged, plate 166 will tend to rotate further rather than toreverse. Since the tendency of plate 166 to'reverse is removed, theaforesaid'clicking action will be avoided.

Crank132, as best seen in Figs. 5, 6, and 7, comprises a check portion200, in the present instance welded or present instance, is contoured tofit about collar20 2 so as -to be pivotally guided thereon. Pin 160extends ,in-

wardly through slot 204 and also through a clamping plate 208 on theopposite side'of cheek 200 from carrier plate 206 and is clamped'thereto.by means of a nut 210, the latter servingto clamp carrier plate 206 andpin 160 in fixed. position relatively to cheek 200. In order to moresecurely fasten pin 160, plate 206 extends beyond slot 204 and has abolt 212 passing through a slot 214, in the present instance outwardlyof slot 204 in crank cheek 20,0. Bolt 212-also passes, through clampingplate 2% and has a nut 216-engaging plate 208. With nuts 216 and 216tightened, pin 160 is securely fastened in relation to cheek'2tl0. If itis desired to change the position of pin 160, this may be done with nuts210 and 216 loosened, pin 160 shifting in substantially a true arc aboutshaft 134 as carrier plate 206 is guided by collar 202 and bolt 212 inslot 214. When the desired adjustment is reached, it is securelymaintained by tightening nuts 210 and 216 as will be apparent. In thisway a crank is provided which is adjustablein position relatively to itsshaft but which is dependable in maintaining its adjustment inthe faceof the rather severe shock loads imparted to it by the selfinterruptingclutch 140. p

Follower 174, as heretofore indicated, forms part of a trip membercomprising in the present instance a lever arm 218 pivoted in a bearingportion 228 preferably supported in above-mentioned plate 138 disposedat a point in a line substantially tangent to the major portion of camsurface or track 168 so that lever 218, resisting any tendency to turnon the partof plate 166, is substantially in a condition of pure tensionor compression. In other words, it is substantially on dead centeras-related to the forces imposed upon it.

. As best seen in Fig. 2, lever portion 218 has a tension spring 222connected therewith adjacent follower 174 and extending, when follower174 is engaged in notch 172, at a large angle to lever arm 218 andanchored to a hook arrangement 224 adjustably'mounted on above-mentionedbracket 14, a nut 226 being operable to change the effective length ofhook element 224 to adjust the tension or strength of spring 222. Spring222 extends in a direction as nearly as practical suitable to provide amajor component of force pulling follower 174 into notch 172 so thatsufficient force is availabe to cause the slight turning of plate 166,hereinbefore described, as follower 174 seats in the .notch 172.

Lever arm 218 has a journal portion extending through bearing 220 andfixed to an arm 228 which extends upwardly and .rearwardly, and isconnected with a rope or the like 230 extending to the tractor so thatclutch 140 may be actuated by the tractor operator. A pull on rope 230will rock arm 228' and accordingly arm 218, thereby removing follower174from notch 1'72 and initiating actuation of the clutch. It will be notedthat as lever arm 218 swings, the angle between spring 222' and lever21% is materially reduced so that the pull of spring 222, while actuallyincreased by the stretching of the spring, in view of the change inangle is reduced in its effect on the lever 218, approaching a deadcenter relation with lever 218 and its bearing 220. .In this way arelatively large force is developed tending to seat follower 174 in thenotches 172 and 170, while avoiding the necessity for an excessive forceor pull on rope 230.

Conditions vary in the application of this invention to various machinesand to meet as many as possible of such variations, certainmodifications are contemplated as indicated in Figs. 8 and 9. In thisinstance, a'clutch 145 has a modified form of plate 166 fixed on a shaft134,

connecting with a crank of any suitable type 132*. A link is pivotedto'an arm 232 which will be assumed to be continuously biased in thedirection indicated. In accordance with the principle explained inconnection with f adjustable crank 132, the downward thrust resulting inlink .130 with crank 132 over center as shown would result in favorableconditions as to latching of plate 166 when the motion of cluutch isinterrupted. Conven= tionally, the position of clutch 14G correspondingto'the lowered position of arm 232 would place crank 132 ;1 80 degreesfrom the position shown in Fig. 8. This, however, assuming a continuousdownward load on link '130, would result in a torque in crank 132. in a'reverse'd direction, the very dimculty which is avoided in the Fig. 8position, this defect being corrected as follows.

Clutch 166 has a notch 172 engaged by a follower 174 to maintain theparts in position for a raised condi: tion in arm 232. Plate 166 alsohas a notch 17!] which is engaged by follower 174 for maintaining arm232 in a lowered position as seen in Fig. 9. While conventionally thenotches 170 and 172 are dimetrically'oppos'ed, in the case of clutchplate 166, notches 170 and 172 are less than 180 degrees apart, passingfrom notch 170 clockwise to notch 172 and, of course, more than 180degrees apart passing in the same direction from notch 172 to notch 170Thus with the parts arranged as shown crank 132 will turn less than 180degrees when clutch 140 is actuated from the position in Fig. 8 to theposition in Fig. 9. The weight of the load on arm 232 and link 130therefore continues to urge crank 132 in a clockwise direction as willbe apparent from Fig. 9, so that the difiiculty of undesired reversingof theclutch plate 165 and continuous disengaging and reengaging orclicking of the clutch is avoided. e I In other words, in view of thenondiametrical arrangement of notches 170 and 172*, crank 132 assumingit to be correctly adjusted in relation to plate i66 will be lockedslightly past dead center when the load is raised and will be lookedslightly before dead center when the load is lowered, both positionscausing the load to tend to rotate the crank in a. forward directionrather than a reverse direction.

The operation of the mechanism is thought to be clear from the foregoingdescription and 'it is clear also that expedients have been provided forfully realizing the objects of the invention, and it is to be understoodthat the same is not intended to be limited by anything in the drawingsor descriptions or, in fact, in any manner except as defined in thefollowing claims.

What is claimed as new and desired of the United States is:

1. In a power lift implement of -the type including 'a mobile frame, anearth working rig element mounted on the frame for up-and-down adjustingmovement respecby' Letters Patent tively into transport and earthworking positions and mechanism for so moving said rig element; thecombination in such mechanism, of a self-interrupting clutch including aconstantly rotating part'and an intermittently rotating part andmechanism adapted, tdmomentarily a connection from said crank pin tosaid earth working rig element for lifting and lowering the latter inresponse to rotations of said crank.

2. In a power lift implement of the type including a mobile frame, anearth working rig element mounted on the frame for up-and-down adjustingmovement respectively into transport and earth working positions andmechanism for so moving said rig element; the combination insuchmechanism, of a self-interrupting clutch including a constantlyrotating part and an intermittently rotating part and mechanism adaptedto momentarily connect the first mentioned part to the second mentionedpart for rotation therewith, control means for said mechanism, means forraising and lowering said rig element from rotation of said secondmentioned part including a crank pin eccentrically disposed in relationto the axis of rotation of said second mentioned part, a crank pincarrier plate having a portion guided for rotation about said axis, saidcrank pin being fixed on said carrier plate, clamping means engaged withsaid carrier plate and adapted. to clamp said carrier plate and saidcrank pin rigidly in one position relatively to said second mentionedpart, said carrier plate and crank pin being shiftable to anotherangularly disposed position when said clamping means are disengaged, anda connection from said crank pin to said earth working rig element forlifting and lowering the latter inresponse to rotations of said crank.

connect the first mentioned part to the second mentioned part forrotation therewith, control means for said mechanism, means for raisingand lowering said rig element from rotation of said secondmentionedfpart including a shaft extending from .and fixed for rotationwith said second mentioned part, a crank element on said shaft includinga crank pin carried by said crank element eccentrically disposed inrelation to the axis of rotation of said shaft, said crank including acheek portion trans-- versely disposed with relation to said'shaft, acrank pin carrier plate juxtaposed withjsaid'cheek portion and having aportion guided for'rotatio'n about the axis of .said shaft, said checkportion providing 'a' slot spaced from said shaft, said crank pinbeingfixed onsaid carrier plate and having a portion extending throughsaid slot, clamping means on said crank pin engaging the side of saidcheck remote from said carrier plate, said cheek providing a second slotspaced radially from the first mentioned slot, and clamping meansengaged with said carrier plate and in second slot, said clamping meansbeing adapted to clamp said carrier plate and said crank pin rigidly inone position relatively to said check, said carrier plate and crank pinbeing 'shiftable to another position when said clamping means aredisengaged, and

3. In a power lift implement of the type including a mobile frame, anearth working rig element mounted on the frame for up-and-down adjustingmovement and mechanism for so moving said rig element, said rig elementbeing constituted to impose on said mechanism a continuous load in onedirection; the combination in such mechanism'of a self-interruptingclutch including a constantly rotating part and an intermittentlyrotating part, a crank connected for rotation with the intermittentlyro- -ating part, and having a first dead-center position when said loadis raised and a second dead-center position when 'said load is lowered,said positions being disposed substantially 180 degrees part, saidintermittently rotating part having a pair of peripherally spaced detentmeans, a clutch tripping member engaged with one of said detent meansfor locking said intermittently rotatable member and said crank in apredetermined position, said tripping member being engageable in anotherposition of said intermittently rotatable member, with the other detentmeans, one of said detent means being so located with relation to saidtripping member as to place said crank, when engaged with said trippingmember in a position slightly past dead center relatively to thedirection of rotation of said clutch with the load in raised position,and the other detent being located substantially less than 180 degreesfrom the first in the direction opposite interrupted by engagement ofsaid tripping member with said detents.

4. In a power lift implement constituted to unpose a continuous load inone direction; the combination of a self-interrupting clutchincluding aconstantly rotating part and an intermittently rotating part, a crankconnected for rotation with the intermittently rotating part, and havinga first dead-centerposition when said load is raised and a I second.dead-center position when said load is lowered,

said positions being disposed substantially degrees apart, saidintermittently rotating part having a pair of peripherally spaced detentmeans, a clutch tripping member engaged-with one of said detent meansfor locking said intermittently rotatable member and said crank in apredetermined-position, said tripping member being engageable in anotherposition of said intermittently rotatable mcmberwith the other detentmeans, one of said detent means being so located with relation to saidtripping member as to place said crank, when engaged with said trippingmember in a position slightly past dead center relatively to thedirection of rotation of said clutch with the load in raised position,and the other detent being located substantially less than 180 degreesfrom the first in the direction opposite to that of the rotation of saidclutch.

References Cited in the file of this patent UNITED STATES PATENTS 10 iHarris May 27, 1919 Davis July 31, 1923 Hendricks et a1 Feb. 25, 1936King Nov. 8, 1938 Strandlund Nov. 28, 1939 Strandlund Nov. 28, 1939Scarlett et a1. June 27, 1944 Hyland et al Dec. 16, 1947 Oehler et al.Mar. 15, 1955 Aber June 5, 1956 FOREIGN PATENTS Germany Feb. 9, 1956Great Britain Feb. 21, 1951 UNITED STATES PATENT @FFICE CERTIFICATION OFCORRECTION Patent No. 2,964,114 December l3 1960 Waldemar J, Meldahl Itis hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected belows Column 7, line 71, before "second" insert said column 8lines 36 and 37, for roating" read rotating same column, line 40, for"part" read apart Signed and sealed this 16th day of May 1961.

(SEAL) Attest:

ERNEST Wo SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents

